WO2009139288A1

WO2009139288A1 - Communication device

Info

Publication number: WO2009139288A1
Application number: PCT/JP2009/058298
Authority: WO
Inventors: 靖志曽我部; 明徳平
Original assignee: 三菱電機株式会社
Priority date: 2008-05-16
Filing date: 2009-04-27
Publication date: 2009-11-19
Also published as: JP5165056B2; JPWO2009139288A1

Abstract

Signals of communication systems having different specifications can be demodulated all at once by using a simple configuration. Provided is a communication device including: an analog unit (1) which receives a plurality of signals between a plurality of communication systems all at once; a demultiplexing unit (3) which demultiplexes the signals received all at once, for each channel; demodulation units (4-6) which select a channel corresponding to each of the communication systems in accordance with a signal of each channel demultiplexed by the demultiplexing unit (3) and demodulates the signal in a communication system unit; a power detection unit (10) which detects a reception power of each channel selected by each demodulation unit and judges with which communication system the local device is to perform communication according to the detection result; and a communication control unit (11) which performs communication control in accordance with the demodulation result of each communication system obtained by each demodulation unit and judgment result obtained by the power detection unit (10).

Description

Communication device

The present invention relates to a communication apparatus capable of communicating with a plurality of communication systems having different specifications.

Conventionally, as a wireless device corresponding to a plurality of systems (applications) in the same frequency band, for example, ETC (Electronic Toll Collection System) / DSRC (Dedicated Short Range Communication) / Vehicle Communication for ITS (Intelligent Transport Systems) There are in-vehicle communication devices that support multiple systems. For example, a method has been proposed in which an in-vehicle communication device has a plurality of transmission / reception units and modulation / demodulation units corresponding to each system, and communicates with a desired system by switching between them (see Patent Document 1 below). In this example, ETC is given the highest priority, and when an ETC signal is detected, the ETC transmission / reception unit and modulation / demodulation unit are forcibly selected.

In addition, for example, a wireless device having a wireless unit corresponding to a plurality of systems in the same frequency band and improving the real-time property at the time of selection by selecting the one having the highest received power has been proposed (Patent Document 2 below). reference). This wireless device is equipped with a radio unit for ETC and DSRC using the ASK (Amplitude Shift Keying) modulation method and a radio unit for inter-vehicle communication using the QPSK (Quadrature Phase Shift Keying) modulation method. Is operated, the signal strength of the received radio wave is detected, and the one with the higher received power is selected for communication.

In addition, as a radio device corresponding to a plurality of systems of different frequency bands, for example, an antenna and a frequency converter unit are provided outside a normal radio device, and the antenna and the frequency converter part are selected and used, and software radio A method of sharing a wireless device portion has been proposed (see Patent Document 3 below).

Similarly, a method different from the above that employs software defined radio has been proposed as a wireless device corresponding to a plurality of systems having different frequencies (see Patent Document 4 below). This software defined radio includes a plurality of programmable signal processing devices, and sets the other signal processing device as a switching destination communication method while communicating with one signal processing device.

The technology of each of the above patent documents includes an antenna, an RF (Radio Frequency) unit, an IF (Intermediate frequency) unit, and a modulation / demodulation unit corresponding to each system in order to communicate with a plurality of systems. The purpose is to perform real-time (seamless) switching by switching circuits and modules to be used. Some technologies aim to reduce the circuit scale by sharing possible parts or applying software defined radio to the baseband part.

Also, as a method for accommodating a plurality of terminals in the same frequency band, for example, there is a collective modulation / demodulation method used in satellite communication or the like. In this method, the frequency band is divided and used by a plurality of terminals. In the repeater, signals from the plurality of terminals are handled by a single radio (see Non-Patent Document 1 below). In the conventional batch modulation / demodulation method, it is necessary to make the reception power from each terminal in the receiver constant, and it is also necessary to synchronize the frame timing. For this reason, it is necessary to perform transmission power control and timing control for each terminal from the receiver side that performs batch modulation / demodulation.

JP 2004-246687 A JP 2007-104043 A Japanese Patent Laid-Open No. 2003-110454 JP 2006-173664 A

However, the conventional technique described above has a problem that the apparatus scale and the circuit scale cannot be reduced because the system cannot be completely shared for all systems having different modulation / demodulation methods.

In addition, the conventional batch modulation / demodulation system described in Non-Patent Document 1 is a system intended to accommodate a plurality of users in the same frequency band, and allocates terminals operating in each system to the plurality of frequency bands. As a result, a plurality of systems can be processed by a single wireless device. However, since the receiver of the radio unit performs gain adjustment such as AGC (Automatic Gain Control) for all received signals at once, if a signal with a low signal level and a high signal are mixed, the A / In D (Analog / Digital) conversion, there is a problem that a signal with a low signal level has a smaller number of bits and a larger quantization error than a high signal. In the same case, there is also a problem that a signal with a low signal level has a poor S / N ratio. On the other hand, as a solution to this, if the control at a constant input level at the receiver input is performed, the power control is performed on the transmission side. There was a problem that notification was necessary. In addition, since the conventional batch modulation / demodulation system is intended to control a plurality of terminals in the same system with a single control unit, a timing control function for synchronizing frame timing is required.

In addition, when adopting OFDM (Orthogonal Frequency Division Multiplexing), there is OFDMA (Orthogonal Frequency Division Multiple Access) as a method for performing batch modulation and demodulation. This method is used in WiMAX, and it is possible to assign a plurality of users in a band by arbitrarily dividing a channel on the frequency axis during OFDM modulation of secondary modulation. However, in the OFDMA system, when performing FFT (Fast Fourier Transform), it is necessary to perform timing control so that all user signals fit in the FFT window with symbol-level resolution. There was a problem that it was necessary to synchronize the time. In addition, since control is performed so that the level at the receiver input terminal is constant, there is a problem that notification for transmission power control is required to the transmission side as described above.

The present invention has been made in view of the above, and an object thereof is to obtain a communication apparatus that collectively demodulates signals of a plurality of communication systems having different specifications with a simple configuration.

In order to solve the above-described problems and achieve the object, the present invention provides a communication apparatus that can be connected to a plurality of communication systems having different specifications, and collects a plurality of signals between the plurality of communication systems. Receiving means, demultiplexing means for demultiplexing the received signals for each channel, and selecting a channel corresponding to each communication system based on the signal for each channel demultiplexed by the demultiplexing means, Demodulating means for demodulating the signal in units of communication systems; power detecting means for detecting received power for each channel selected by the demodulating means; and determining a communication system in which the apparatus communicates based on a detection result; Control means for performing communication control based on a demodulation result for each communication system obtained from the demodulation means and a judgment result obtained from the power detection means.

According to the present invention, it is possible to reduce the size of the apparatus and eliminate the need for a channel search. Therefore, it is possible to shorten the time until the start of communication, and to enable high-speed channel switching. Play.

FIG. 1 is a diagram illustrating a configuration example of a communication apparatus. FIG. 2 is a diagram showing frequency allocation for ITS in the current 5.8 GHz band. FIG. 3 is a diagram illustrating an example of received power. FIG. 4 is a diagram illustrating a case where communication is performed by selecting a system having the maximum power. FIG. 5 is a diagram illustrating an example of the time required for the channel search. FIG. 6A is a diagram illustrating a state in which a vehicle performs road-to-vehicle communication and vehicle-to-vehicle communication in the vicinity of an intersection. FIG. 6B is a diagram illustrating a state in which the vehicle performs road-to-vehicle communication and vehicle-to-vehicle communication near the intersection. FIG. 7A is a diagram illustrating an example of received power. FIG. 7B is a diagram of an example of received power. FIG. 8 is a diagram illustrating a configuration example of a communication device. FIG. 9 is a diagram illustrating a configuration example of the analog unit. FIG. 10A is a diagram illustrating an example of received power. FIG. 10B is a diagram of an example of received power. FIG. 10C is a diagram illustrating an example of received power.

Hereinafter, an embodiment of a communication device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a communication device according to the present invention. Specifically, as an example of the communication device, an in-vehicle communication device corresponding to each system of ETC / DSRC / inter-vehicle communication in the 5.8 GHz band is shown. 1 includes an analog unit 1, a demultiplexing unit 3, an ETC demodulating unit 4, a DSRC demodulating unit 5, an inter-vehicle demodulating unit 6, an ETC control unit 7, DSRC control unit 8, inter-vehicle control unit 9, power detection unit 10, and communication control unit 11. Note that the in-vehicle communication apparatus of FIG. 1 adopts a single carrier method in accordance with an existing ETC / DSRC roadside machine.

The analog unit 1 receives signals for the entire band for ITS or a desired band, and outputs the received signals as baseband digital signals. The demultiplexing unit 3 in the collective demodulation unit 2 demultiplexes the input signal and divides it into channels corresponding to each system. Here, the demultiplexing unit 3 is, for example, a multi-rate filter that can set an arbitrary bandwidth for each channel. The ETC demodulator 4, the DSRC demodulator 5, and the inter-vehicle demodulator 6 select a channel used in the corresponding system of ETC / DSRC / inter-vehicle communication, and the signal input from the demultiplexer 3 Performs demodulation corresponding to the system. In addition, a signal (demodulated data sequence) is output to a corresponding control unit connected to the subsequent stage, and power information of the channel selected above is output to the power detection unit 10.

The ETC control unit 7, the DSRC control unit 8, and the inter-vehicle control unit 9 correspond to an ETC system, a DSRC system, and an inter-vehicle communication system, respectively, and error correction and frame processing are performed on signals output from the respective demodulation units. And outputs the result to the communication control unit 11.

The power detection unit 10 obtains a communicable system based on the power information for each system output from each demodulation unit of ETC / DSRC / vehicle-to-vehicle communication, and outputs the result to the communication control unit 11. The communication control unit 11 performs communication control based on the output from each control unit of ETC / DSRC / inter-vehicle communication and the output from the power detection unit 10.

FIG. 2 is a diagram showing frequency allocation for ITS in the 5.8 GHz band. Conventional frequency allocation is performed assuming road-to-vehicle communication only, and as shown in FIG. 2, for uplink (vehicle communication device → roadside device) and downlink (roadside device → vehicle communication device) Seven channels (U1 to U7, D1 to D7) are defined. Regarding inter-vehicle communication, no frequency is assigned at this stage. For this reason, the following description will be made on the assumption that one or more of the specific use or unused channels among the channels shown in FIG. 2 can be allocated.

Note that ETC / DSRC / vehicle-to-vehicle communication operates independently of each other, and the power of each channel (system) is different from the viewpoint of the in-vehicle communication device on the receiving side. In addition, frame intervals and clock timings are independent (asynchronous between systems) for each system.

Next, the operation of the in-vehicle communication device configured as described above will be described. When the analog unit 1 of the in-vehicle communication device receives the signal of the entire band for ITS shown in FIG. 2 (or the desired band if the range of the used band is known), the analog unit 1 converts it into a baseband digital signal. The data is converted and output to the batch demodulation unit 2. The demultiplexing unit 3 of the collective demodulation unit 2 demultiplexes the input signal into signals for each channel. Each demodulator performs processing in parallel, outputs a demodulated data sequence to each control unit connected to the subsequent stage, and outputs power information for each system to the power detector 10. Each control unit for ETC / DSRC / vehicle-to-vehicle communication identifies a unique word that is a known pattern signal for system discrimination inserted in the demodulated data series, thereby identifying an application used in each system, The result is output to the communication control unit 11 connected to the subsequent stage.

Here, operations of the power detection unit 10 and the communication control unit 11 of the in-vehicle communication device will be described in detail. FIG. 3 is a diagram illustrating an example of received power at the time of channel detection observed in the in-vehicle communication device. Here, DSRC (D3 / U3) and inter-vehicle communication (U7) signals in the vicinity and ETC (D1) and DSRC (D4) signals in the distance are observed.

Since ITS normally communicates with neighboring systems, for example, a threshold is set for received power as shown in FIG. In this case, the power detection unit 10 excludes a system of a channel whose received power is equal to or less than a threshold value from communication targets even if it is correctly demodulated. Therefore, the power detection unit 10 determines that the DSRC (D3 / U3) and the inter-vehicle communication (U7) are systems in which the own device communicates, and notifies the communication control unit 11 accordingly. The communication control unit 11 performs control for starting DSRC communication and inter-vehicle communication based on the output from each control unit connected in the previous stage and the notification from the power detection unit 10.

Further, in the case where the in-vehicle communication device is designed to communicate with only one system, for example, the maximum value of the received power is detected, and communication is performed with the system of the channel that maximizes the power. FIG. 4 is a diagram illustrating a case where communication is performed by selecting a system having the maximum power in the example of the received power illustrated in FIG. 3. In this case, the power detection unit 10 determines DSRC (D3) as the maximum power, and notifies the communication control unit 11 to that effect. The communication control unit 11 performs control for starting DSRC communication based on the output from each control unit connected to the preceding stage and the notification from the power detection unit 10. In the case where the maximum value detection is adopted, in a communication environment where there is no system operating in the vicinity, there is a possibility that a weak radio wave or noise from a distance is erroneously detected as the maximum value. In order to avoid this, for example, the detected maximum value is compared with an appropriately set threshold value, and if the maximum value is equal to or less than the threshold value, it is determined that communication is impossible. In the communication environment, the channel is not limited to the above determination method. For example, when the control unit corresponding to the channel with the maximum power cannot detect a unique word or when there is an error in the demodulated data, the channel It is good also as judging that communication in is impossible.

Next, the difference from the conventional method in the channel search when the collective demodulation as described above is performed will be described. FIG. 5 is a diagram illustrating an example of a time required for channel search when there are a plurality of systems. In the conventional system, the in-vehicle communication device needs to perform channel allocation processing with a roadside unit for road-to-vehicle communication (ETC / DSRC) or a nearby in-vehicle communication device that performs inter-vehicle communication prior to communication. For this reason, the in-vehicle communication device needs to search for a channel used by the roadside device and a nearby in-vehicle communication device. For example, in the reception state of FIG. 2, since there are four channels that can be used for road-to-vehicle communication (ETC / DSRC), the in-vehicle communication device determines which channel D1-D4 is used by the roadside unit. In addition to searching, a search is made as to which channel is used by a nearby in-vehicle communication device for inter-vehicle communication. Therefore, as shown in the conventional method of FIG. 5, the time required for the channel search becomes long, and it takes time until the communication starts.

On the other hand, the in-vehicle communication device of this embodiment demodulates all the ITS band (or the desired band) signals all together, so channel search processing is unnecessary and communication is started only by synchronization processing. can do. Therefore, compared to the conventional method of searching one by one until a corresponding channel is found, it is possible to significantly reduce the time until communication is started.

As described above, in the present embodiment, since a single analog unit handles signals of different frequencies, the circuit scale can be reduced and the apparatus can be downsized.

Further, in this embodiment, since the signals of the entire band for ITS (for the desired band when the use range is known) are demodulated in a lump, channel search becomes unnecessary and communication is started. Can be shortened. In addition, since a plurality of channels are always demodulated, synchronization processing at the time of channel switching becomes unnecessary, and high-speed channel switching becomes possible.

Further, in this embodiment, the received power is compared with the threshold value, and the channel having the power higher than the threshold value is detected, so that transmission power control to the communication partner is unnecessary. Thereby, since it is not necessary to change the existing ETC / DSRC roadside machine, the existing equipment can be used as it is. In addition, the adoption of a single carrier eliminates the need for timing synchronization at the symbol period level for all in-vehicle communication devices and roadside devices, eliminating the need to change the modulation method and allowing the existing ETC / DSRC roadside devices to be used as they are. It is.

In this embodiment, channel detection is performed for all channels that are assumed to be used for ITS. However, for detection of road-to-vehicle communication, only the downlink signal from the roadside unit is used as a criterion. May be. As a result, the circuit scale can be reduced. However, in this case, depending on the detection timing, the in-vehicle communication device may perform communication on the uplink. The transmission signal from the in-vehicle communication device is generally smaller than the transmission signal of the roadside unit, but this uplink signal may exceed the threshold depending on the positional relationship between the host vehicle, the adjacent vehicle, and the roadside unit. Therefore, in such a case, the detection process may be performed on the uplink signal. In this case, the signal detection accuracy may increase.

Further, in this embodiment, the case where the bandwidth per channel of each system is the same has been described as an example, but it is possible to cope with different bandwidths by setting a multi-rate filter as a demultiplexing unit. is there.

In this embodiment, ITS is taken as an example and a case where a plurality of systems within the same system band is assumed has been described. However, even when a plurality of system bands arranged adjacently or discretely are assumed. Applicable.

Embodiment 2. FIG.
In the first embodiment, signals in the entire band (or a desired band) for ITS are monitored and demodulated at once, and communication is performed with a system in a channel whose received power exceeds a threshold value. In the present embodiment, a priority for each system is introduced to select a system for communication.

Currently, ITS uses (1) ETC, which is a charging system, as a preferential use method for applications that avoid interference between road-to-vehicle communication (ETC / DSRC) and inter-vehicle communication. (2) Safety and security at intersections Has proposed that DSRC be used preferentially. Therefore, in this embodiment, as an example, priority is given in the order of “ETC> DSRC> inter-vehicle communication”, and the communication control unit 11 performs control according to this priority. The priority may be another order. The configuration of the in-vehicle communication device is the same as that in FIG. In the present embodiment, it is assumed that the in-vehicle communication device has a specification for communicating with only one system.

Hereinafter, the operation of the in-vehicle communication device in the present embodiment will be described. FIGS. 6A and 6B are diagrams illustrating how the vehicle performs road-to-vehicle communication and vehicle-to-vehicle communication in the vicinity of the intersection. FIGS. 7A and 7B are both for in-vehicle use. It is a figure which shows an example of the received power observed in a communication apparatus.

In FIG. 6A, for example, the vehicle 21 that is the host vehicle is communicating with the vehicle 22 using the channel U7. At this time, the power detection unit 10 of the in-vehicle communication device mounted on the vehicle 21 observes the signal power as shown in FIG. At this time, since the power of the ETC system is not observed, the power detection unit 10 determines that it is outside the ETC communication area. Moreover, although the power of DSRC (D3 / U3) is observed, since the received power is equal to or less than a predetermined threshold, the power detection unit 10 determines that it is outside the DSRC communication area. The power detection unit 10 outputs these determination results to the communication control unit 11. The communication control unit 11 continues the inter-vehicle communication with the vehicle 21 based on these results.

Thereafter, when the vehicle 21 moves and enters the communication area of the roadside unit 23 for DSRC installed in the vicinity of the intersection as shown in FIG. 6B, the power detection unit 10 of the in-vehicle communication device The signal power is observed as shown in -2. In this case, since the power of the ETC system is not observed, the power detection unit 10 determines that it is out of the ETC communication area. However, since the power of DSRC (D3) is equal to or greater than the threshold, the vehicle enters the DSRC communication area. The communication control unit 11 is notified of the determination result. The communication control unit 11 performs control for stopping the vehicle-to-vehicle communication that has been continued with the vehicle 22 based on the determination result and the priority order, and then uses the channel D3 / U3 to communicate with the roadside device 23. Control for starting DSRC communication is performed.

Further, for example, when the vehicle 21 does not perform inter-vehicle communication with the vehicle 22 and the received power is in the state shown in FIG. 7-2, the power detection unit 10 determines that the vehicle is within the DSRC communication area. And it judges that it exists in the communication area between cars, and notifies the communication control part 11 of a judgment result. The communication control unit 11 performs control for starting DSRC communication with the roadside device 23 using the channel D3 / U3 based on the determination result and the priority order. Here, since the priority is “DSRC> car-to-car communication”, even when the power of car-to-car communication exceeds the threshold, control for connecting to the DSRC communication is performed without performing car-to-car communication.

As described above, in the present embodiment, the power states of a plurality of channels within a desired band are simultaneously monitored, and priorities are assigned among the systems, and the highest priority is given to systems whose power exceeds a threshold value. The system with the highest priority was selected for communication. As a result, an ITS system with little mutual interference can be realized, and seamless application change can be realized even when the connected system is changed.

Embodiment 3 FIG.
In the second embodiment, the power states of a plurality of systems (channels) in a desired band are simultaneously monitored, and the system having the highest priority among the systems whose power exceeds the threshold is selected for communication. . In the present embodiment, in addition to this, the analog unit extracts a signal of a desired system and selectively outputs the signal of the desired system and the signal received at once.

FIG. 8 is a diagram illustrating a configuration example of the third embodiment of the communication device according to the present invention. As in the first and second embodiments, as an example of the communication device, an in-vehicle communication device corresponding to each system of ETC / DSRC / inter-vehicle communication in the 5.8 GHz band is shown. In the present embodiment, it is assumed that the in-vehicle communication device has a specification for communicating with only one system.

8 is provided with an analog unit 1B instead of the analog unit 1 and a communication control unit 11B instead of the communication control unit 11, as compared with the on-vehicle communication device of FIG. The analog unit 1B receives signals for the entire band for ITS or a desired band, and outputs the received radio wave as a baseband digital signal. The communication control unit 11B performs the same processing as the communication control unit 11, and further selects the analog signal 1B and the AGC based on the output from each control unit connected to the previous stage and the notification from the power detection unit 10. Output a control signal.

FIG. 9 is a diagram illustrating a configuration example of the analog unit 1B of the in-vehicle communication device illustrated in FIG. The analog unit 1B includes a down converter 31, a channel filter 32, a switch 33, an AGC 34, a down converter 35, and an A / D conversion unit 36. The down converter 31 converts an input RF (Radio Frequency) signal into an IF (Intermediate Frequency) signal. The channel filter 32 filters the IF signal and passes only the set channel. The switch 33 switches the output (signal / channel) to be passed in accordance with the select signal sent from the communication control unit 11B, and only the output on the set side of the output of the down converter 31 and the output of the channel filter 32 is selected. Pass through. An AGC (Automatic Gain Control) 34 adjusts the gain of the input signal in accordance with the AGC control signal from the communication control unit 11B and outputs it. The down converter 35 converts the input signal into a baseband signal. The A / D conversion unit 36 performs analog / digital conversion.

Next, the operation of the in-vehicle communication device configured as described above will be described. Also in the present embodiment, as in the case of the second embodiment, priority is given in the order of “ETC>DSRC> inter-vehicle communication” as an example, and the communication control unit 11B performs control according to this. In the present embodiment, it is assumed that no ETC exists in the DSRC communication area.
The channel filter 32 of the analog unit 1B is set to extract the channel D3 in the initial state, and the switch 33 allows the output from the down converter 31 to pass in the initial state. Yes.

For example, in the situation of FIG. 6-1, the power detection unit 10 of the in-vehicle communication device mounted on the vehicle 21 observes the signal power as shown in FIG. 10-1. 10-1, FIG. 10-2, and FIG. 10-3 are diagrams showing examples of received power observed in the in-vehicle communication device. At the time of FIG. 10-1, since the power of the ETC system is not observed, the power detection unit 10 determines that it is outside the ETC communication area. Moreover, although the power of DSRC (D3 / U3) is observed, since the received power is equal to or less than a predetermined threshold, the power detection unit 10 determines that it is outside the DSRC communication area. The power detection unit 10 notifies the communication control unit 11 of these determination results. The communication control unit 11 continues the inter-vehicle communication with the vehicle 21 based on these results.

Thereafter, when the vehicle 21 moves and enters the communication area of the DSRC roadside unit 23 installed in the vicinity of the intersection as shown in FIG. 6B, the power detection unit 10 of the in-vehicle communication device, for example, The signal power is observed as shown in FIG. In this case, since the power of the ETC system is not observed, the power detection unit 10 determines that it is outside the ETC communication area. On the other hand, since the power of DSRC (D3) is equal to or greater than the threshold, it is determined that the host vehicle has entered the DSRC communication area. The power detection unit 10 notifies the communication control unit 11B of these determination results. The communication control unit 11B performs control for stopping the inter-vehicle communication that has been continued with the vehicle 22 based on the notified result, and is connected to the roadside unit 23 using the channel D3 / U3. Control for starting DSRC communication is performed. Then, the communication control unit 11B outputs a select signal for selecting the output of the channel filter 32 toward the switch 33 of the analog unit 1B in order to perform DSRC communication.

By the way, since the analog unit 1B receives a signal in which signals from a plurality of systems are combined, the received signal is amplified (attenuated) so as to be optimal for the A / D conversion range as in the conventional collective demodulation method. ), The desired signal is not always optimal. For example, in the case shown in FIG. 9-2, the signal power of the channel U7 (inter-vehicle communication) is larger than the signal power of the desired channel D3 (DSRC). It is difficult to take out in a state.

Therefore, the analog unit 1B according to the present embodiment performs processing for extracting the DSRC signal in an optimal state. Specifically, first, the switch 33 is set to pass the output of the down converter 31 in the initial state, but the output of the channel filter 32 is passed according to the select signal from the communication control unit 11B. Performs processing to switch settings. Next, the AGC 34 performs gain adjustment suitable for the input signal in accordance with the AGC control signal from the communication control unit 11B, and outputs the adjusted signal. Thereafter, predetermined processing is performed by the down converter 35 and the A / D conversion unit 36, and finally, the DSRC signal is output in an optimal state from the analog unit 1B.

Thereafter, when the DSRC communication is completed in the vehicle 21, the communication control unit 11 </ b> B outputs a select signal for selecting the output of the down converter 31 to the switch 33. Thereby, it returns to the state which can detect the signal of all the systems.

As described above, in the present embodiment, priority is given to a plurality of systems, the output of the analog unit is controlled according to the priority, and only a desired system signal can be extracted. Thereby, unnecessary system signals can be deleted, and desired signals can be extracted in an optimum state. In addition, it is possible to suppress the deterioration of characteristics that occur when the received power varies from system to system, which is a problem with the conventional batch demodulation method, and it is not necessary to control the transmission power to keep the received power of the system (channel) constant. become. Therefore, the existing ETC / DSRC roadside machine can be used as it is. Furthermore, the adoption of a single carrier eliminates the need for timing synchronization at the symbol period level in all in-vehicle communication devices and roadside devices, and also eliminates the need to change the modulation method.

As described above, the communication apparatus according to the present invention is useful for a communication apparatus that communicates with a plurality of systems having different specifications, and is particularly suitable for a communication apparatus that collectively demodulates signals of a plurality of systems.

DESCRIPTION OF SYMBOLS 1,1B Analog part 2 Collective demodulation part 3 Demultiplexing part 4 ETC demodulation part 5 DSRC demodulation part 6 Inter-vehicle demodulation part 7 ETC control part 8 DSRC control part 9 Inter-vehicle control part 10 Electric power detection part 11, 11B

Communication control unit

21, 22 Vehicle 23 Roadside device 31, 35 Down converter 32 Channel filter 33 Switch 34 AGC
36 A / D converter

Claims

A communication device connectable to a plurality of communication systems having different specifications,
Receiving means for collectively receiving a plurality of signals between the plurality of communication systems;
A demultiplexing means for demultiplexing the received signals for each channel;
A demodulation unit that selects a channel corresponding to each communication system based on a signal for each channel demultiplexed by the demultiplexing unit, and demodulates the signal in communication system units;
Power detection means for detecting a received power for each channel selected by the demodulation means, and determining a communication system in which the apparatus communicates based on a detection result;
Control means for performing communication control based on a demodulation result for each communication system obtained from the demodulation means and a determination result obtained from the power detection means;
A communication apparatus comprising:
The power detection means includes
The received power for each channel selected by the demodulating means is compared with a predetermined threshold, and a communication system corresponding to a channel having a power higher than the threshold is determined as a communication system in which the apparatus communicates, The communication device according to claim 1, wherein notification is performed.
The power detection means includes
A communication in which the own apparatus communicates with a communication system corresponding to a channel having the largest power among the channels having a power higher than the threshold by comparing the received power for each channel selected by the demodulation means with a predetermined threshold. The communication apparatus according to claim 1, wherein the communication apparatus is determined to be a system and notifies the control means.
When giving priority to the plurality of communication systems individually,
The control means includes
The communication apparatus according to claim 1, wherein communication control is performed based on the priority in addition to a demodulation result for each communication system obtained from the demodulation unit and a determination result obtained from the power detection unit. .
When giving priority to the plurality of communication systems individually,
The control means includes
The communication apparatus according to claim 2, wherein communication control is performed based on the priority in addition to a demodulation result for each communication system obtained from the demodulation means and a determination result obtained from the power detection means. .
The receiving means includes
Selection means for selectively outputting a first signal that is an analog reception signal received by an antenna and a second signal that is an analog signal of a predetermined channel extracted from the first signal;
Gain adjusting means for adjusting the gain according to the output signal of the selecting means;
A reception processing means for outputting a digital signal generated by a predetermined reception process using the analog signal after the gain adjustment, as the batch received signal;
With
The control means includes
5. The communication apparatus according to claim 4, further comprising: switching control for switching the output of the selection unit in accordance with a communication system in which the device itself performs communication, and AGC control for the gain adjustment unit.
The receiving means includes
Selection means for selectively outputting a first signal that is an analog reception signal received by an antenna and a second signal that is an analog signal of a predetermined channel extracted from the first signal;
Gain adjusting means for adjusting the gain according to the output signal of the selecting means;
A reception processing means for outputting a digital signal generated by a predetermined reception process using the analog signal after the gain adjustment, as the batch received signal;
With
The control means includes
6. The communication apparatus according to claim 5, further comprising: switching control for switching the output of the selection unit in accordance with a communication system in which the device itself performs communication, and AGC control for the gain adjustment unit.
The communication apparatus according to any one of claims 1 to 7, wherein the plurality of communication systems are communication systems having the same system band.
9. The communication apparatus according to claim 8, wherein the plurality of communication systems are a plurality of communication systems including ETC (Electronic Toll Collection System), DSRC (Dedicated Short Range Communication), and inter-vehicle communication.
The communication device according to any one of claims 1 to 7, wherein the plurality of communication systems are communication systems of a plurality of system bands arranged adjacently or discretely.